From db68f0d85d48adcf9ff03f2cc2dbc0e8a1fb4c99 Mon Sep 17 00:00:00 2001
From: miaolz123 <miaolizhao@126.com>
Date: Mon, 28 Sep 2020 19:40:20 +0800
Subject: [PATCH] feat: add ip package

---
 example/main.go |   1 +
 net/ip.go       | 102 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/ip_test.go  |  28 +++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 net/ip.go
 create mode 100644 net/ip_test.go

diff --git a/example/main.go b/example/main.go
index 604e3d8..fe58652 100644
--- a/example/main.go
+++ b/example/main.go
@@ -10,6 +10,7 @@ import (
 	_ "github.com/gxxgle/go-utils/json"
 	_ "github.com/gxxgle/go-utils/log"
 	_ "github.com/gxxgle/go-utils/math"
+	_ "github.com/gxxgle/go-utils/net"
 	_ "github.com/gxxgle/go-utils/path"
 	_ "github.com/gxxgle/go-utils/pool"
 	_ "github.com/gxxgle/go-utils/proxy"
diff --git a/net/ip.go b/net/ip.go
new file mode 100644
index 0000000..67fa3f0
--- /dev/null
+++ b/net/ip.go
@@ -0,0 +1,102 @@
+package net
+
+import (
+	"net"
+)
+
+var (
+	privateIPNets []*net.IPNet
+)
+
+func init() {
+	AddPrivateIPNets(
+		"10.0.0.0/8",
+		"172.16.0.0/12",
+		"192.168.0.0/16",
+		"100.64.0.0/10",
+		"fd00::/8",
+	)
+}
+
+func AddPrivateIPNets(ips ...string) {
+	for _, ip := range ips {
+		if _, ipnet, err := net.ParseCIDR(ip); err == nil {
+			privateIPNets = append(privateIPNets, ipnet)
+		}
+	}
+}
+
+func IsPrivateIP(ip net.IP) bool {
+	for _, ipnet := range privateIPNets {
+		if ipnet.Contains(ip) {
+			return true
+		}
+	}
+	return false
+}
+
+func GetLocalIPs() []net.IP {
+	nets, err := net.Interfaces()
+	if err != nil {
+		return nil
+	}
+
+	ips := []net.IP{}
+
+	for _, n := range nets {
+		if n.Flags&net.FlagUp != net.FlagUp {
+			continue
+		}
+
+		inAddrs, _ := n.Addrs()
+		for _, a := range inAddrs {
+			ip := GetIPFromAddr(a)
+			if ip == nil {
+				continue
+			}
+
+			if ip.IsLoopback() {
+				continue
+			}
+
+			if ip.IsUnspecified() {
+				continue
+			}
+
+			ips = append(ips, ip)
+		}
+	}
+
+	return ips
+}
+
+func GetIPFromAddr(addr net.Addr) net.IP {
+	switch v := addr.(type) {
+	case *net.IPAddr:
+		return v.IP
+	case *net.IPNet:
+		return v.IP
+	default:
+		return nil
+	}
+}
+
+// FormatIP format "0.0.0.0" to real private ip, like: "192.168.xx.xx"
+func FormatIP(s string) string {
+	ip := net.ParseIP(s)
+	if ip == nil {
+		ip = net.IPv4zero
+	}
+
+	if !ip.IsUnspecified() {
+		return ip.String()
+	}
+
+	for _, ip := range GetLocalIPs() {
+		if IsPrivateIP(ip) {
+			return ip.String()
+		}
+	}
+
+	return ip.String()
+}
diff --git a/net/ip_test.go b/net/ip_test.go
new file mode 100644
index 0000000..8804bc8
--- /dev/null
+++ b/net/ip_test.go
@@ -0,0 +1,28 @@
+package net
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsPrivateIP(t *testing.T) {
+	type check struct {
+		input    string
+		expected bool
+	}
+
+	checks := []check{
+		{input: "", expected: false},
+		{input: "0.0.0.0", expected: false},
+		{input: "127.0.0.1", expected: false},
+		{input: "192.168.0.0", expected: true},
+		{input: "192.168.255.255", expected: true},
+		{input: "192.169.0.0", expected: false},
+	}
+
+	for _, c := range checks {
+		assert.Equal(t, c.expected, IsPrivateIP(net.ParseIP(c.input)), c.input)
+	}
+}